Mnemonics in trigonometry

The sine, cosine, and tangent ratios in a right triangle can be remembered by representing them as strings of letters, for instance SOH-CAH-TOA in English: One way to remember the letters is to sound them out phonetically (i.e. /ˌsoʊkəˈtoʊə/ SOH-kə-TOH-ə, similar to Krakatoa).

[citation needed] An alternate way to remember the letters for Sin, Cos, and Tan is to memorize the syllables Oh, Ah, Oh-Ah (i.e. /oʊ ə ˈoʊ.ə/) for O/H, A/H, O/A.

"[2] All Students Take Calculus is a mnemonic for the sign of each trigonometric functions in each quadrant of the plane.

with n = 0, 1, ..., 4 for sine and n = 4, 3, ..., 0 for cosine, respectively:[9] Another mnemonic permits all of the basic identities to be read off quickly.

Starting at any vertex of the resulting hexagon:Aside from the last bullet, the specific values for each identity are summarized in this table: